Windshield wipers are a standard feature on the majority of motor vehicles in use today, and are used to clear vehicle windows of various types of dirt and debris. For windshield wipers to function properly, they must be supplied with a jet of windshield wiper fluid that helps to dissolve the dirt and debris and carry the material off of the window, assisted by the motion of the windshield wipers. If not cleaned, dirty windshields in motorized vehicles can seriously impair a driver's field of vision. Effective windshield wipers are particularly important in the trucking industry, where large vehicles with heavy loads are operated for extensive periods, creating significant safety and liability issues.
While conventional windshield wiper systems operate effectively under normal conditions, they can become ineffective when confronted with either cold ambient temperatures that cause the wiper fluid to freeze on the vehicle window, or particularly troublesome material such as impacted insects or road grime that are difficult to remove. Application of wiper fluid to a cold windshield can be particularly disastrous, as the sudden formation of a layer of frozen fluid on the windshield can render the windshield completely opaque.
Various devices and methods have been used in the art to provide a spray of heated wiper fluid onto the windows of a vehicle. For example, most vehicles are equipped with a defrost feature that blows hot air inside the vehicle and onto the windshield. This, however, is a relatively inefficient and slow way of heating the windshield. Others have tried to heat windshield wiper fluid using electrical devices, such as heat elements, and in some cases have combined these with other pumps and distribution systems. See, for example, U.S. Pat. No. 5,509,606, which describes a container into which washing fluid from a reservoir is pumped and in which the fluid is electrically heated by an electric element before spraying onto a windshield. U.S. Pat. No. 4,090,668 provides another example, which describes a windshield washing and de-icing system in which a pump transfers washer fluid from a reservoir into a container. Heated engine coolant is passed through a conduit in the reservoir, and an electric resistance wire further heats the fluid whenever the temperature drops below a minimum value.
These systems, and others found in the art, are generally expensive, cumbersome to install, and may require drilling and modifications to the vehicle chassis. Furthermore, they require electrical current, generally from the vehicle's battery, which may decrease the life expectancy of the vehicle's battery and may result in the battery not having sufficient energy to start the car under cold conditions. Use of electrical current is also inefficient, and there is often a significant delay from the time the unit is activated to the point where hot fluid is actually generated. The hot fluid volume generated by these procedures is minimal, and there may be an additional warming delay between each activation.